STEP to STL: How to Convert STEP to STL Files
Learn more about these two file types and how to make the conversion to STL format.
STEP (.STP or STandard for the Exchange of Product Model Data) is a widely employed file type that fully represents 3D design data. It is viewed as the most reliably interoperable data transfer tool between CAD (Computer Aided Design) and CAM (Computer Assisted Manufacturing) systems. CAD and CAM systems use a wide range of proprietary and shared formats as their “native” file types. STEP has been the best of these for two decades, displacing IGES (Initial Graphics Exchange Specification).
STL (STereo Lithography or Standard Triangle Language or Standard Tessellation Language) format is the “standard” file type used by the majority of 3D printers in the mid and low price range. It’s an older format that is limited in some ways but sufficient for communicating shape (without color or texture information). It is universally accepted and very reliable. STLs store the surface of an object as geometric data for a series of points. This representation generally results in triangular subsurfaces which form a net that describes the external 3D shape. The output gives no information about thickness, color, or texture. Therefore, it’s not a “design” format but rather a simplified communication tool.
When you have an STP file and you need to convert it to an STL format for your slicer software, several software tools are available. Most CAD software that supports saving in STEP format also supports options for STL export, making the process relatively straightforward.
In this article, we will provide some general instructions for converting STEP to STL. We will provide an example using SOLIDWORKS, a popular piece of CAD software. We will also explain the two file formats in more detail and highlight their differences.
Before You Get Started
Generally, we recommend not converting your STEP files to STL for manufacturing. STEP files inherently contain more useful data, such as units and solid data. From a manufacturing side, we can use STEP files to create high-resolution mesh files for printing to ensure the highest print quality. STEP files are also typically required for subtractive manufacturing processes like CNC machining.
At Xometry, your STEP file will cover all your bases, including 3D printing, machining, sheet cutting, and more. So, if you're planning on using our services, there may be no need to convert your files at all! If you want to proceed anyway, then continue with the steps outlined in the sections below.
1. Open the STEP file in your CAD software.
To convert STEP to STL, the first step is finding the STEP file on your computer. When you've located it, right-click and select "open with" and choose a CAD software on your PC that supports opening STEP. Alternatively, you should be able to open the file directly from within your CAD program or drag and drop it into the workspace to open it.
2. Open the file export settings.
Once your model is loaded into your software, navigate to the file export options. Usually, these settings are found under the "File" menu option. Depending on your software, the export settings may either be under "Save As..." or "Export." It is important that you do not select the standard "Save" option, as this will simply save the file in the current format.
4. Check for and configure STL export options.
After selecting the STL format for export, check for any additional export options your software offers. For example, in SOLIDWORKS, clicking the "Options" button on the export file module opens an additional module for configuring the STL file. These settings can directly impact the resolution and quality of the converted STL file, so be sure to examine them closely if they are available.
5. Save the file to complete the conversion.
Now that you've configured your settings for a good export, you can go ahead and save the file! This should complete the conversion process. You can check that the conversion was successful by opening the STL in a 3D viewer on your computer or by uploading your STL to the Xometry Instant Quoting Engine® and using our online 3D viewer to review the model. Your STL file can be instantly quoted for one of our many 3D printing processes.
What Is an STL File?
An STL file is an ASCII format file that originated with 3D Systems' development of 3D printers. It was developed to communicate the printing requirements to 3D Systems' machines. STL files use the same basic methodology for communication of 3D objects that OBJ uses—but at a lower level of detail. It contains no color or texture information and has a slightly more disjointed file structure. Mesh information for the triangles to construct the 3D model contains 3-point (x-y-z) information for each vector. The “normal” information defines which face of the resulting triangle is outward facing. Nonstandard binary formats of STL have also been developed, which adds to the methods of encompassing color data into the file, but these are not commonly used.
What Is a STEP file?
STEP is a powerful 3D design file system that offers great interoperability across a wide range of platforms. These files provide 3D model construction data and metadata in an ASCII format defined by ISO 10303-242:2014 (STEP standard reference). STEP files are commonly used for quoting and for process advisory purposes by service providers. They generally prefer to receive 3D data in one of the interoperable 3D CAD/CAM formats. This is because the creation of STL files can contain errors, so their process is slicker if they handle this stage. STEP's advantage over most formats is its great interoperability. A STEP file stores the complete mechanical design, kinematics, and process planning, as well as metadata for the part/assembly. This complete data set makes it much more than a communication method and enables complete and detailed part design, which can be used directly in multiple CAD and CAM packages.
Programs That Can Open STEP Files
There are several programs that can open STEP files. Any software that can open STEP files can convert them to a range of formats. Examples are:
- CAD Packages: Most if not all CAD packages can open STEP files. Some of these CAD packages are: SOLIDWORKS, Catia, Creo (formerly ProE), AutoDesk Fusion, Siemens NX (formerly UniGraphics), Onshape, and more.
- .STP Viewers: .STP Viewers (both online and offline) offer a lightweight approach for those who need to see but not modify much. These include FreeCAD, Tinkercad, LibreCAD, SketchUp, and of course, you can even use the 3D model viewer built into our quoting engine by uploading your files to Xometry.
Best STEP to STL File Converters
There are some easily accessible platforms and software that work well for STEP to STL conversion. We recommend starting with the following:
- Onshape Free: Onshape is a lightweight cloud-based CAD package. When using the free version, the design/print files will be stored in a public directory in the cloud. This happens when the CAD capabilities are used or the files are saved in Onshape. To keep work private and secure, you may need to upgrade to a paid plan. If you choose to go with Onshape, be sure to check out Xometry's add-in for it! You can learn more about using Xometry within Onshape by visiting our Onshape add-in webpage.
- FreeCAD: This is a widely used and powerful CAD/CAM design package that serves well as a format converter. FreeCAD handles a very wide range of formats. It also offers some great analysis, modification, and repair tools.
- GOM Inspect: This is another capable analysis and repair tool. There are many levels of function to explore that a regular user may find invaluable.
Converting a STEP file to an STL file is sometimes necessary when working with 3D printer slicers that only recognize STL to prepare a print. The conversion can take less than a few seconds, depending on complexity and file size. For most files, setting up directories and uploading the files into the software can take longer than the conversion itself.
How Xometry Can Help
We hope you found this article informative, especially if STEP to STL file conversion was a mystery to you prior to reading it.
At Xometry we actually accept many different native file formats, including STEP and STL! This makes it easy to upload your CAD files for instant quotes without going through conversions. In fact, we actually prefer users upload STEP files whenever possible as they can be used for quoting and manufacturing both additive processes like 3D printing, and subtractive processes like CNC machining. If you're looking for custom-made parts, you can get an instant quote by uploading your native files to the Xometry Instant Quoting Engine® today!
Summary
Disclaimer
The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.